This is one of Heinlein's first novels, published as a book in 1948, it would be his second novel, and actually it first appeared in serialized form in 1942. So I'd agree he's not at the top of his form here, although it's interesting to see themes and tropes here that would later come to flower in his later novels. (Among other things this is the first appearance of that Heinlein aphorism, "An armed society is a polite society.") There are echoes here too, of Aldous Huxley's Brave New World, published in 1931 over a decade before as this deals with the issues of eugenics. For me at least, there's no such thing as a bad Heinlein novel. I find them all readable and interesting, despite seeing their flaws. This isn't one I can't see rereading, and it certainly wouldn't make my top ten list of his best novels. Even so, this one has its charms in the play of ideas and in an inventive and imaginative future.